Mobile telecommunications devices, such as smart-phones, tablet computers, laptop computers, etc., can commonly communicate using a cellular telecommunications network. Such a cellular network is typified by long distance communications networks over licensed spectrum. In some cases, mobile telecommunications devices may also or alternatively use a wireless point-to-point communications network such as a wireless local-area network (WLAN), which facilitates short-distance communications using unlicensed spectrum. For example, a WLAN may be implemented at least in part by Wi-Fi or Bluetooth technologies.
A typical example of a mobile telecommunications device is a smartphone that has a data connection over a cellular network, but at the same time may implement voice-over-IP (VoIP) over a WLAN for voice communications in certain situations.
There are a number of reasons that a user may desire to utilize a WLAN for voice communications. As an example, the user may be at a location where quality of service over a cellular telecommunications network is not as good or reliable as service over an available WLAN. As another example, the user may determine that voice communications over a WLAN may cost less than the same voice communications over a cellular telecommunications network, e.g., long distance calling charges may be cheaper via WLAN than over a cellular telecommunications network.
The ability to access emergency response services by dialing 9-1-1 is a vital component of public safety and emergency preparedness. The Federal Communications Commission (FCC) has established a set of rules and regulations that require service providers to deliver enhanced emergency (E911) services to their subscribers. In particular, service providers are required to provide a current location of a 9-1-1 caller to emergency services. In the case of mobile devices, however, the current location of the user can be difficult to determine.
When 9-1-1 is dialed over a cellular network, a service provider attempts to determine the position of the calling user by triangulation. This results in a set of geographical coordinates, such as a latitude and a longitude, which is sent to an emergency response service. In some cases, the geographical coordinates may be converted to a street address that is provided to the emergency response service.